Wrongly-fitted washer led A300 to veer off runway

Incorrect installation of a washer in the nose-gear torque link axle of an Airbus A300B4 freighter caused a chain reaction that ended with the aircraft’s veering off the runway at Bratislava.

The Air Contractors twinjet had landed on runway 22 following a service from Leipzig on 16 November last year.

About 6s after the aircraft touched down with its nose-gear the crew felt an increasingly strong vibration. As it decelerated to 85kt, and the thrust reversers were stowed, the aircraft veered left.

Attempts to counter the yaw with the rudder and nose-wheel steering were unsuccessful and the aircraft left the runway. Its nose-gear hit a manhole and collapsed.

None of the three crew members was injured.

French investigation authority BEA found evidence that a washer in the axle of the torque link – the connecting arms which prevent free rotation of the nose-gear – had been installed the wrong way round.

As a result it did not fit snugly onto the axle and subsequent operations caused the axle nut to unscrew and separate. The nose-gear, freed from the constraint, started to oscillate and the crew lost directional control.

BEA found that a maintenance procedure on the nose-gear had been performed 26 days before the accident. The presence of a detailed diagram, it says, was not enough to prevent the incorrect washer assembly. The A300 (EI-EAC) performed 37 cycles between the maintenance and the accident.

Airbus informed the inquiry that two similar incidents occurred during 2008-09, involving an A300-600 in Vietnam and an A310 in Pakistan, with only “minor” consequences.

While differential braking can be used as a steering backup below 70kt, the captain of the Air Contractors A300 told the inquiry that the event happened too quickly to consider this option.